The present invention relates to a wireless transmitter/receiver circuit system for a wireless audio equipment, and more particularly to such a wireless transmitter/receiver circuit system which enables a wireless headphone or speaker system to automatically trace floating frequency upon receiving of a transmitting signal, so as to achieve a quality receiving.
In a wireless audio system, a high-frequency transmitter is installed in the main unit of the audio system for audio output wirelessly, and a high-frequency receiver is installed in the headphone or speaker system of the audio system to receive radio output signal from the high-frequency transmitter at the main unit. This design has numerous drawbacks as outlined hereinafter.
1. The oscillator of the high-frequency transmitter tends to be affected by temperature, causing a xe2x80x9cfrequency floatingxe2x80x9d. The straight line receiving operation of the high-frequency receiver, as shown in FIG. 5, cannot accurately trace the floating frequency, thereby causing a receiving distortion. Therefore, a correction is needed when the audio system is started again, or when the high-frequency transmitter is controlled to change the channel (frequency).
2. Because the high-frequency transmitter of the transmitter and receiver system does not have the function of encrypting transmitting signal and the high-frequency receiver of the transmitter and receiver system is not capable of automatically scanning and comparing received signal, the transmitter and receiver system cannot fit frequency floating.
3. Because an additional matching circuit is used to match with the transmitting antenna of the transmitter, the structure of the transmitter is complicated, and the operation of the transmitting antenna tends to be affected by other oscillator means.
The present invention has been accomplished to provide a wireless transmitter/receiver system which eliminates the aforesaid drawbacks. According to one aspect of the present invention, the transmitter circuit of the wireless transmitter/receiver system uses a stereo multiplexer and a 32Kxcx9c1 MHz select to encrypt transmitting signal. According to another aspect of the present invention, the receiver circuit of the wireless transmitter/receiver system comprises a digital logic, a scan driver, an auto gain control, a stereo decode, a VCO tone, a pilot select, and a pilot make test. During operation, the receiver circuit automatically scan transmitting signal from the transmitter circuit, automatically adjust its scanning range, and automatically tracing the floating of the received signal, so as to achieve a high receiving performance. According to still another aspect of the present invention, the receiver circuit has a concealed receiving antenna installed in a metal shell for direct coupling by air. This design eliminates the installation of a complicated matching circuit. According to still another aspect of the present invention, the transmitter circuit uses a level control power standby to automatically turn the circuit to a standby mode when no transmitting signal is outputted. According to still another aspect of the present invention, the circuit system achieves the function of xe2x80x9cautomatically tracing floating frequencyxe2x80x9d, it is not necessary to correct the receiving manually.